In known electromagnetic switching devices, the seal is established, for example, by introducing O ring seals or by media-tight extrusion coating of the coil. One disadvantage of the arrangements known from the prior art is that an increased assembly complexity and thus also higher costs are caused by the additionally required components. The risk, which should not be underestimated, also exists that fluctuations arising during the injection molding process may result in leaks.
An electromagnetic adjusting device is known from DE 10 2006 015 233 B4, in which the yoke section and the core section are implemented as a yoke/core section manufactured as a single piece, whereby the complex axial centering of the components relative to each other is eliminated. A magnetic short circuit is generated between the core and the yoke, which has only a limited impact on efficiency, due to additional geometric arrangements, but does not mitigate this impact entirely. The bearing unit in this case is mounted in the housing.
In DE 10 2007 061 862 A1, a bearing sleeve is integrated into the switchable magnet arrangement with the aid of a welding method. All other parts are inserted into an injection mold, and extrusion-coated with a plastic compound, so that they are held fixedly against each other. A pressure compensation is to be implemented in the magnet without any compensating bores in the armature piston. For this purpose, it is proposed that the armature and/or the yoke and/or the conical guiding element and/or the bearing is/are surrounded by a magnetically conductive, media-permeable material.
As a result, the devices according to the prior have an increased assembly complexity. Due to the injection molding process and the media-permeable material, a complete and secure sealing of the magnet against the surroundings may not be achieved.